The Opelousas courier., 1887-10-08
GATHERING GOLD.
An Explanation Of the Mining
Methods in Colorado.
Machinery Used in Separating
the Metal From the Ore.

dt DIeckenfluSe, COl., the OCner day.,
says correspondent in the Globe Demo-
crat, | saw the Jumbo stamp-mill, and
there got a fair insight into the method
of getting the gold out of what is called
free milling ore. The stuff that comes
from the mine is first put through a
crusher, which breaks it up fine, and the
product is then run through rollers
which pulverizes it, though, perhaps,
coarsely. From the rollers it falls to
the lower floor, upon which the mortars
are located. At the Jumbo mill the dirt
is fed to the stamps by hand; in other
mills it falls through chutes which work
automatically, and never feed more than
is necessary at a time. The stamps are
arranged in batteries Of five stamps each.
They work up and down in oak case
pents, and their motions are regulated
by cams on a shaft geared to the motive
machinery. The stamps weigh from $50
to 900 pounds, according to the charac-
ter of the ore treated. Water flows into
the mortars and out of them down
tables to the waste fumes which carry
the refuse away. Stamps in this,
country run as slow as thirty drops
a minute, and seldom over sixty;
in California they drop seventy to 100
times a minute. They cost from $3.50
for a five-stamp prospecting mill to $780,
900 for a 100-stamp mill. The dirt be-
ing fed into the mortars is pounded and
pounded by the stamps; the silica,
porphyry and other refuse is carried off
by the water, but the gold is caught BY
two copper plates coated with quicksil-
yer that line the sides of the mortar; any
of the precious metal that escapes from
the mortar may be caught IN the AXIS
feet copper plates that are quicksilver
coated and lie on the table over which
the refuse is carried. Some of the gold
gets away, of course, but the Jumbo
saves as much as 80 per cent. o. its gold,
and Mcfarland is now building mills
| which he claims will save 95 per cent. Of
essayed value of ore.
Commentators are used where the ore
is too low grade to pay for smelling in its
crude state. By concentrating a $40 or
$12 ore may be handled so that the mill
product which will represent six or
seven tons in ore, may be worth $40 to
$50 per ton. The scheme is very sim
| pie. The crushed and rolled ore are fed
through stutes to revolving screens,
ranging in size from three-fourths inch
openings to one eighth. Each of these
screens has a trough and a chute which
feads e.iig boz The jig boxes work on
an eccentric and keep up a spasm-like
motion. There is a screen in each about
six inches from the top, and this screen
is covered with lead or other heavy ore
material, which prevents the silica
porphyry and other light stuff from 60
ing through. The motion shakes the
metal to the bottom of the hoxes, where
It remains until valves in the bottom are
opened and the concentrates are re-
moved. This machine, like all the
others called by different names, and
known as triumphs, frue vanners, bud
dies, bump plates, ETC., is an application
of the we'll known law of specific gravl
ty; the heaviest material falls to thu
bottom in all these machines, and thu
light stuff goes dancing away on thu
water. The bump plate which i
claimed to be a new invention by Pete
Mcfarland, is a large steel plate set a
n incline of a few degrees; the orc
fed to the lower part of the place from
water trough and as the high enc
bumps it carries forward and mp ovel
the top Of the plate the heavy concen
trates.